Centerless grinder



Feb. 10, 1931. c s ET A 1,791,713

CENTERLESS GRINDER Filed April 17, 1926 2 Sheets-Sheet 2 Jim/2Z1 Caster ieslelfiflnninyer I 6mm.

Patented Feb. 10, 1931 UNITED STATES PATENT OFFICE JOHN E. CASTER AND LESTER F. NENNINGER, OF CINCINNATI, OHIO, ASSIGNORS, BY

MESNE ASSIGNMENTS, TO THE CINCINNATI GRINDERS INCORPORATED, OF CIN- CINNATI, OHIO, A CORPORATION OF OHIO CENTERLESS GRINDER Application filed April 17,

This invention relates to improvements in grinding machinery and has particular reference to a novel and improved method and apparatus for producing finished workpieces of circular form in cross-section without the use of terminal work-centers.

A further object of the invention is the provision of an improved apparatus which may be employed toform a given cylindrical surface concentric either with an internal bore or with previously formed exterior surfaces on proximate portions of the workpiece.

Another object of the invention is the provision of improved mechanism for production of work-pieces to a given predetermined axis which will insure a constant supported urge of the work-pieces in the direction of the grinding wheel.

A. further. object of the invention is the provision of novel and improved means for supporting and positioning the work during the grinding operation and for facilitating the ready removal of the work from the machine, at the completion of the grinding.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification taken in connection with the accompanying drawings and it will be understood that we may make any modifications in the specific structural details hereinafter described within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Figure 1 is a side elevation of a machine embodying these improvements.

Figure 2 is an elevation of the work-supporting mechanism and associate parts.

Figure 3 is a verticalsection as on the line 3-3 of Figure 2.

Figure 4 is a fragmentary sectional on the line 44 of Figure 2.

Figure 5 is a view partially in elevation and partially in section illustrating the control cam for the quick adjustable work limiting member, and

Figure 6 is a fragmentary view il1ustrating a different form of mounting and adjustment for the regulating wheel.

view

"1926. Serial No. 102,765.

In the drawings in which similar characters of reference are employed to denote corresponding parts throughout the several views, the letter A designates the base of a conventional form of centerless grinding machine having the bracket portion B in which is j ournale'd the grinding wheel 0. The bed is further provided with a slide section D on which is rotatably mounted the regulating wheel E. Suitable conventionalmechanism such as the adjusting screw F and pilot wheel G serve for setting or adjustment of the regulating wheel E with respect to the grinding wheel C to vary the width of work-receiving throat between these parts. In addition, a lever H may be coupled with the screw F and slide D to impart a relative in and out movement to the regulating wheel E in the conventional manner as ordinarily employed in connection-with commercial centerless grinding machines of the type here illustrated.

In ordinary centerless grinding it is customary to support the work in the throat between the grinding and regulating wheels in a free or floating manner as on a suitable work-rest and allow it to automatically round up and determine its own center or axis which will ordinarily be that of the mass of the piece being ground.

As distinguished from this previously employed process, the present invention coninvention difficulty has been experienced in grinding a work-piece of this nature, due to the trouble in properly centering, supporting and rotating the member with respect to the grinding wheel in ordinary center grinding machines.

To overcome these difliculties the present machine embodies certain means for limitof different forms, in that the stopfor the ing the movement of the predetermined work axis in the direction of the grinding wheel, in conjunction with means which will con tinuously urge the work toward the grinding wheel, but will be capable of yielding as to eccentric portions of the work for example, to prevent am or breakage during the grindmg.

Supported on a slide 12 carried by the bed A is a work controlling bracket 13. This bracket has a central work-rest blade supporting portion 14 with a slot 15 for the work-rest 16. This work rest is formed with an angularly related upperface 17 for peripheral engagement with the work-piece 10 during the grinding. Adjusting devices 18 make it possible to vary the vertical position of the work-rest with respect to the supporting bracket 13. while clamp screws 19 aid in locking it in desired adjusted position. In addition to the work-rest support, the bracket is provided at points laterally displaced from said support with the lugs 20 supporting the trunnions 21 of the work or arbor controlling members. These members are shown as two in number, substantially alike in structure and comprise the basal arm 22 having the upright portion 23 provided with a bore or passage 24 and terminal forwardly extended lateral flanges 25. These flanges are connected by the trunnions 26 for the idler rolls 27, there being a pair of vertically spaced rolls contained largely within the space inclosed by the flanges. In addition, the flanges have an integral hood portion or guard 28 overlying and protecting the trunnion bearing, so far as possible from the grinding fluid which is supplied to the work as through nozzle J.

By reference particularly to Figure 2 of the drawings it will be noted that the pivotally supported members 23 are disposed one on each side of the grinding wheel and that as indicated in Figure 3 the rolls 27 project slightly beyond the grinding wheel into the work throat adjacent the work-supporting rest or blade 16. To control the exact position occupied by the rolls use is made of an adjusting screw 29, having a knurled head 30. This screw extends downwardly through the bore 24 in portion 23, having threaded engagement with a portion of said bore and having a lower abutment end-31 for engagement with a suitable abutment or stop on the bracket 13. The stops at opposite sides are right hand member in Figure 2, or what may be termed the rear of the machine is normally a mushroom plug 32 fitting in a suitable socket 33 in the base, inasmuch as this member has only to be adjusted to .a certain predetermined position and remain in this position. A compression spring 3 1 fitting partially within a' socket 35 in the work-rest support 14 and partially in an alined socket 36 in the arm 22, urges the arm 22 downwardly to hold the abutment 31 against its limiting member.

To facilitate introduction and removal of work from the grinding throat the left hand or front work-limiting member in place of engaging a fixed contact plug preferably engages the periphery of a cam 37 secured on cam shaft 38, journaled in bracket 13 and oscillatable as' by handle 39. When the handle is in raised position the high point of the cam will be in engagement with the lower end of the screw, holding the rolls in their forward position in the throat, as is shown in Figure 3. However, when the handle is laterally swung toward the left as the machine is viewed from the front, this will bring a low point on the cam beneath the screw, allowing arm portion 22 to swing downwardly as actuated both by gravity and by spring 34. This movement is sufiicient to shift the rolls out of axial alinement with the maximum diameter of a work-piece within the grinding throat, so as to permit of ready insertion or removal of a work-piece from said throat.

In the use of the resent machine the work to be ground, consi ering a sleeve or bushing such as 10 "for example, is'mounted upon an arbor 11 and is then introduced between the grinding and regulating wheels when the latter are in a separated position, the work rest ing on the upper inclined face of the work blade 17 and being urged by gravity in the direction of the re 39 is then shifte to bring the front member 23 forward, so that its rolls will be alined with the rolls of the fixed or rear limiting member. The regulating wheel is then moved inward urging the work-piece toward the grinding wheel. At the same time the grinding wheel is rotated at a high or grinding rate of speed and with its operative surface adjacent the work blade, moving downwardly. As the wheels are brought toward each other the work-piece will be rotated by the regulating wheel and its surface removed to the extent which the regulating wheel urges it in the direction of the grinding would naturally round up and establish its.

final center or axis through a substantially uniform peripheral reducing action. It is frequently the case however, when the seclating wheel E. Handle 0nd surface is to be ground concentric with the inner surface to within limits of one or two ten thousandths of an inch that the two surfaces are not originally concentric. The work cannot therefore be allowed to float within the grinding throat in the usual manner. The rolls 27 are therefore so adjusted through the screw 29 as to engage the arbor 11 when any point on the work-piece has been cut down to the prescribed radius length from its final determined center.- This means that the movement of the work-piece toward the v grinding wheel is therefore limited by interunyielding material usually a suitably bonded abrasive which will positively force the work toward the grinding wheel. In the present instance however, due to the limitation of movement of the work in one direction it is impossible to utilize a rigid regulating wheel. On the contrary, use is made either of a rubber or yielding wheel as indicated in Figure 3, or else the regulating wheel slide has a lost motion connection as by the bushing 40 with the adjusting screw F'and is urged against the forward edge of the bushing by a resilient or yielding device such as a spring or springs 41 on the bed, so that it may accommodate itself to irregularities in the radial size of the work-piece in the direction of the regulating wheel and jamming of the parts will be prevented. It will of course be understood that this resilient or yielding mounting of the regulating wheel may be at any point in the train of supports between the wheel and bed and not necessarily at the point indicated in Figure 6, the main essential being either that the wheel itself have a yielding surface or that some connection be employed which will produce the effect of yielding surface as respects the workpiece.

From the foregoing description taken in connection with the drawings, it will there fore be apparent that the work-piece may be readily mounted on a supporting arbor roperly fitting the interior thereof and the evice as a unit loosely placed within the grinding throat with the work=piece itself in contact with the work-supporting blade and surface of the regulating wheel. The regulating wheel is then brought inward, urging the work-piece in the" direction of the grinding wheel, the movement of the surface of the work-piece in that directionbeing limited by interengagement of the idler rolls 27 and the projecting ends of the arbor, so that it is impossible for the work to be ground below determined size or to be ground to any circle except one concentric with its inner diameter; also, that during this operation the regulating wheel surface will remain in constant en-- gagement with the work controlling the rotation thereof during the grinding and yielding to the necessary extent for eccentric portions of the work as respects the predetermined axis .when those portions are 0.1 the regulating Wheel side, while urging the work as an entirety toward the grinding wheel, sothat these eccentric portions will be properly cut off or removed.

Of course, it will be understood that while this description has just been made as of a hollow bushing or the like, supported on an arbor, that the operation would be in all respects the same if this were a shoulder portion of large diameter on an integral shaft, whose ends had previously been concentrically established, in that in this instance the terminal portions of the work-piece itself in place of the arbor, would ride upon the rolls 27.

On the completion of the grinding, the regulating wheel is withdrawn in the usual manner to open up the grinding throat for withdrawal of the work-piece and at the same time the front restraining member or stop is caused to recede from alinement wit-h the outer periphery of the work, allowing the work-piece to be axially withdrawn.

To assist in discharge of the completed work with its arbor from the machine, use may be made of the hunter or ejector 42 s1id able in a guide bracket 43 on the main bracket 13.- This bracket is actuable as by the intermediately pivoted lever 44, whose lower end is engaged by the manual ejector push rod v 45. This push rod is slidably supported by portions of the same lugs 21 that serve as mountings for the trunnions of the swinging stop members 23.

It will of course be understood that conventional and automatic regulating wheel controlling and ejector operating mechanisms might be used for actuation of the parts herein described, in place of the manual actuation to which particular reference has been made, the particulainmanner of application of shifting force thereto not effecting the basic principles here involved.

We claim:

1. A grinding machine including a grinding wheel, a work-supporting blade disposed adjacent the grinding wheel, and extending transverselyof the operative face thereof to peripherally engage a work piece and support same against the thrust of the grinding wheel, means for resiliently urging work on the blade in the direction of the grinding wheel and means for limiting the movement of the work as resiliently urged.

2. A mechanism of the character described, including opposed grinding and regulating wheels forming a work-receiving throat therebetween, a work-support disposed within the throat, a plurality of means exteriorly of the throat and projecting intoalinement therewith for positioning a work-piece within the throat, means for adjustab'ly varying the position of one of said work limiting means and additional means for shifting the other of said work-limiting means into and out of alinement with the throat.

3. The combination with a centerless grinder, including opposed grinding and regulating wheels and an intermediate work-support in which said three parts together position a work piece for precision grinding thereof to a diameter determined by the relationship of said three point bearing thereof, oijwork-controlling means therefore, comprising arms pivotally supported at the sideg of the grinding wheel, work-limiting rolls carried by said arms and projecting adjacent the grinding wheel for engagement with workpiece extensions and means for adjusting the position of said arms with respect to the work-piece.

4. The combination with a centerless grinder, including opposed grinding and regulating wheels and an intermediate work-support, of work-controlling means therefore, comprising arms pivotally supported at the sides of the grinding wheel, work-limiting rolls carried by said arms and projecting adjacent the grinding wheel for engagement with work-piece extensions, and means for independently adjusting the position of each of the arms with respect to the plane of the operative surface of the grinding wheel.

5. The combination with a centerless grinder, including opposed grinding and regulating wheels and an intermediate work-support, of work-controlling means therefore, comprising arms pivotally supported at the sides of the grinding wheel, work-limiting rolls carried by said arms and projecting adjacent the grinding wheel for engagement with the workpiece extensions, means for adjusting the position of said arms with respect to the work-piece and means for moving one of the said'arms into and out of work-engaging position. I

6. A machine of the character described, including a grinding wheel, an opposed yieldable regulating wheel, a work-supporting blade intermediatesaid parts, means adjacent the grinding wheel for limiting the movement of the work in the direction of the grinding wheel, means for withdrawing said limiting device from operative position and means for ejecting a work-piece when the limiting means is withdrawn.

7. A machine of the character described, including a grinding wheel, a bracket adjacent the grinding wheel, a work-supporting blade carried by the bracket, a yieldable regulating wheel adjacent the blade for urging work thereon in the direction of the grinding wheel and means for limiting said move ment of the work, including an arm pivoted to the bracket and having an upright portion bearing a stop member, and means for regulating the pivotal movement of the arm to vary the position of the stop member with.

respect to the operative surface of the grinding wheel.

8. A machine of the character described, including a grinding wheel, a bracket adjacent the grinding wheel, a work-supporting blade carried by the bracket, a yieldable regulating wheel adjacent the blade for urging work thereon in the direction of the grinding wheel, means for limiting said movement of the work, including an arm pivoted to the bracket and having an upright portion bearing a stop member, means for regulating the pivotal movement of the member with respect to the operative surface of the grinding wheel, and quick acting means for moving the stop into and out of operative position.

9. A machine of the character described, including a bed, a grinding wheel supported thereby, a bracket rising from the bed adjacent the grinding wheel and bearin a worksupport-ing blade, an arm pivote to the bracket having an upright portion projecting adjacent the blade and terminating in a work limiting device, an adjusting device carried by the upright portion for controlling the pivotal movement of the parts to vary the operative position of the stop, and a cam member cooperating with the adjusting device for releasing the arm to permit of pivotal movement of the device into inoperative position.

10. A machine of the character described, including opposed grinding and regulating wheels formin a work-receiving throat and a work-supportlngblade projecting within the throat, a pair of similar sto devices disposed at opposite sides of the grmding wheel and each including an upright portion bearing spaced antifriction rolls for engagement with a work-piece extension, adjusting screws carried by said devices for varying the position of the rolls with respect to the operative face of the grinding wheel to control the positioning of a work-piece, a fixed abutment for engagin one of said adjusting screws to fixedly limit its cooperating stop member and a variable abutment engaging the other of said i stop members, whereby said latter may be readily shifted into and out of operative position by variance of the engagement of the abutment and adjusting screw.

11'. An attachment for a centerless grinder, including a bracket having a central portion carrying a work-supporting blade and having ear ortions laterally displaced as respects said lilade supporting portion, stop arms having trunnions engaged in said ears andhaving work-engagingportions, and an ejector device carried by the bracket and'having an operating portion slidably engaged in said ears substantially as and for the purpose described. I i

12. A work-limiting device for application to a grinder, comprising a bracket bearing a work-engaging blade and sto members p1votally supported by the' brac et at the ends of the blade, said members having antifricsupported on the blade, means resiliently urging said stop members in a-direction away from the blade, adjustable means for independently urging the members toward the blade and withdrawable abutment cooperating with one of the adjustable means, whereby the resilient means may be allowed to force the rolls into inoperative position or may be quickly compressed to restore the rolls to their previous operative position.

14. A grinding machine of the character described, including a grinding wheel operable at a high or grinding rate of speed, a work rest disposed adjacent the grinding wheel having its operative surface disposed in opposition to the direction of the movement of the grinding wheel to receive the thrust of the grinding wheel against the work, means for continuously urging the work on the support in the direction of the grinding wheel, means adjacent the grinding wheel for limiting the movement of the-work as so urged, and a yieldable connection in theework urging mechanism whereby undue pressure of the.

work against the limiting stop is prevented.

15. A grinding machine of the character described, including a grinding wheel, a slipport for peripheral engagement with a rotary work piece disposed adjacent the grinding wheel and adapted to engage the surface of the work as the latter is being ground, means in opposition to the grinding wheel for engagement with the surface of the work as it is being acted on to urge the work transversely of the support in the direction of the grinding wheel, and means exterior to the grinding wheel for engagement with projecs tions on the Work to limit the movement of the work axis in the direction of the grinding wheel, said work urging mechanism including a work contacting member, an actuator capable of a definite amount of movement toward and from the grinding wheel and a yieldable connection between the work contacting member and actuator, substantially as and for the purpose described.

ably shiftin the regulating wheel in the direction of the grinding wheel to move the work on its support and means adjacent the grinding wheel in position to engage axialprojections on the work and limit the axial approach of the work to the grinding wheel.

17. A machine for the production of articles of circular form in cross section, including a grinding wheel rotatable at a grinding rate of speed and a regulating wheel rotatable at a slow work controlling rate of speed,

said Wheels having opposed operative faces,

means for supporting a work piece between said faces for rotation about a fixed axis, and means for resiliently urging one of said wheels'toward the other to maintain contact between said wheel and the work piece.

In witness whereof, we hereunto subscribe our names.

JOHN E; (EASTER. LESTER F. NENNINGER.

16. A centerless grinder for the production 

